Monolithic semiconductor switches and method for manufacturing

ABSTRACT

One aspect is monolithic semiconductor switches and method for manufacturing. One embodiment provides one semiconductor die with a first and a second FET. One of source/drain of the first FET and one of source/drain of the second FET are electrically coupled to at least one contact area at a first side of one semiconductor die, respectively. The other one of source/drain of the first FET, a gate of the first FET, the other one of source/drain of the second FET and the gate of the second FET are electrically coupled to contact areas at a second side of the one semiconductor die opposite to the first side, respectively. The contact areas of the other one of source/drain of the first FET, of the gate of the first FET, of the other one of source/drain of the second FET and of the gate of the second FET are electrically separated from each other, respectively.

BACKGROUND

Field effect transistors (FETs) are included in semiconductor chips of avast variety of semiconductor device applications. For example, in motordrivers, DC-converters and rectifiers, FETs are used as semiconductorswitches in half-bridge configuration including a low-side switch and ahigh-side switch. In view of further developments of these applications,there is a need for increasing the integration level while ensuringappropriate device characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of embodiments and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments andtogether with the description serve to explain principles ofembodiments. Other embodiments and many of the intended advantages ofembodiments will be readily appreciated as they become better understoodby reference to the following detailed description. The elements of thedrawings are not necessarily to scale relative to each other. Likereference numerals designate corresponding similar parts.

FIG. 1 illustrates a simplified view of a portion of a semiconductordevice including a first FET as a high-side switch and a second FET as alow-side switch according to one embodiment.

FIG. 2 illustrates a schematic view of a portion of a semiconductordevice including an n-type lateral DMOS (Double-Diffused Metal OxideSemiconductor) high-side switch and an n-type lateral DMOS low-sideswitch.

FIG. 3 illustrates a schematic view of a portion of a semiconductordevice including an n-type lateral DMOS high-side switch and an n-typetrench DMOS low-side switch having a Schottky contact area within a cellarray of the low-side switch according to one embodiment.

FIG. 4 illustrates a schematic cross-sectional view of a portion of asemiconductor device including a p-type trench MOSFET high-side switchand an n-type trench MOSFET low-side switch according to one embodiment.

FIG. 5 illustrates a simplified cross-sectional view of a portion of asemiconductor device including an n-type trench MOSFET high-side switchand an n-type trench MOSFET low-side switch with n-type polysiliconspacers according to one embodiment.

FIG. 6 illustrates a schematic cross-sectional view of a portion of asemiconductor device including an n-type trench MOSFET high-side switchand an n-type trench MOSFET low-side switch with n-type semiconductorzones adjoining sidewalls of the trenches, respectively, according toone embodiment.

FIG. 7 is a schematic cross-sectional view of a portion of asemiconductor device including an n-type trench MOSFET high-side switchand an n-type trench MOSFET low-side switch for low voltage applicationsaccording to one embodiment.

FIG. 8A illustrates a schematic plan view of a semiconductor deviceincluding one semiconductor die having a first FET and a second FEThoused in a CanPAK package.

FIG. 8B illustrates a schematic cross-sectional view of thesemiconductor device illustrated in FIG. 8A along a cut line AA′.

FIG. 8C is a schematic cross-sectional view of the semiconductor deviceillustrated in FIG. 8A along a cut line BB′.

FIG. 8D is a simplified plan view of a printed circuit board (PCB)having the semiconductor device of FIG. 8A mounted thereon as well as aninput capacitance.

FIG. 9 illustrates a schematic cross-sectional view of the portion ofthe semiconductor device illustrated in FIG. 2 having an inputcapacitance mounted thereon.

FIG. 10A illustrates a schematic plan view of a semiconductor deviceincluding one semiconductor die mounted on a lead frame, an inputcapacitance mounted on the one semiconductor die and conductive clipsinterconnecting the one semiconductor die and external pins according toone embodiment.

FIG. 10B illustrates a schematic plan view of the semiconductor deviceof FIG. 10A in a moulded state.

FIG. 11 illustrates a schematic plan view of a semiconductor deviceincluding one semiconductor die mounted on a lead frame, an inputcapacitance mounted on the one semiconductor die and conductive clipsinterconnecting the one semiconductor die and the external pins, thelead frame being exposed to an outside of a package.

FIG. 12 illustrates a schematic plan view of a semiconductor deviceincluding one semiconductor die mounted on a lead frame, conductiveclips interconnecting the one semiconductor die and external pins, andan input capacitance mounted on the conductive clips, the lead framebeing exposed to an outside of a package.

FIG. 13 illustrates a schematic plan view of a semiconductor deviceincluding one semiconductor die mounted on a lead frame, conductiveclips interconnecting the one semiconductor die and external pins, aninput capacitance mounted on the conductive clips and two gate pinsassigned to different loads on a low-side switch of the onesemiconductor die, the lead frame being exposed to an outside of apackage.

FIG. 14 illustrates a schematic plan view of a semiconductor deviceincluding one semiconductor die mounted on a lead frame, conductiveclips interconnecting the one semiconductor die and external pins, aninput capacitance mounted on the one semiconductor die and two gate pinsassigned to different loads on a low-side switch of the onesemiconductor die.

FIG. 15 is a simplified flow chart illustrating a method ofmanufacturing a semiconductor device according to one embodiment.

FIGS. 16A to 16K illustrate schematic cross-sectional views of onesemiconductor die for illustrating a method of manufacturing asemiconductor device including a first trench FET and a second trenchFET in half-bridge configuration in accordance with one embodiment.

DETAILED DESCRIPTION

In the following Detailed Description, reference is made to theaccompanying drawings, which form a part hereof, and in which is shownby way of illustration specific embodiments in which the invention maybe practiced. In this regard, directional terminology, such as “top,”“bottom,” “front,” “back,” “leading,” “trailing,” etc., is used withreference to the orientation of the Figure(s) being described. Becausecomponents of embodiments can be positioned in a number of differentorientations, the directional terminology is used for purposes ofillustration and is in no way limiting. It is to be understood thatother embodiments may be utilized and structural or logical changes maybe made without departing from the scope of the present invention. Thefollowing detailed description, therefore, is not to be taken in alimiting sense, and the scope of the present invention is defined by theappended claims.

It is to be understood that the features of the various exemplaryembodiments described herein may be combined with each other, unlessspecifically noted otherwise.

In the following embodiments of the semiconductor device andmanufacturing method are described in connection with the Figures.

One embodiment of a semiconductor device described herein includes onesemiconductor die with a first and a second FET, wherein one ofsource/drain of the first FET and one of source/drain of the second FETare electrically coupled to at least one contact area at a first side ofone semiconductor die, respectively. The other one of source/drain ofthe first FET, a gate of the first FET, the other one of source/drain ofthe second FET and the gate of the second FET are electrically coupledto contact areas at a second side of the one semiconductor die oppositeto the first side, respectively. The contact areas of the other one ofsource/drain of the first FET, of the gate of the first FET, of theother one of source/drain of the second FET and of the gate of thesecond FET are electrically separated from each other, respectively.

The above and still further features and advantages of embodiments willbecome apparent upon consideration of the following definitions,descriptions and descriptive features, wherein like reference numeralsin the various Figures are utilized to designate like components. Whilethese descriptions go into specific details, it should be understoodthat variations may and do exist and would be apparent to those skilledin the art based on the descriptions herein.

FIG. 1 schematically illustrates a portion of a semiconductor device 100including one semiconductor die 101. The one semiconductor die 101includes a first FET 110 and a second FET 120, wherein one connection111 of source/drain of the first FET 110 and one connection 121 ofsource/drain of the second FET 120 are electrically coupled to a contactarea 130 at a first side 102 of the one semiconductor die 101,respectively. The other connection 112 of source/drain of the first FET110, a gate 113 of the first FET 110, the other one connection 122 ofthe second FET 120 and the gate 123 of the second FET 120 areelectrically coupled to contact areas 135, 136, 137, 138 at a secondside 103 of the one semiconductor die 101 opposite to the first side102, respectively. The contact areas 135, 136, 137, 138 of the other oneconnection 112 of source/drain of the first FET 110, of the gate 113 ofthe first FET 110, of the other one connection 122 of the second FET 120and of the gate 123 of the second FET 120 are electrically separatedfrom each other, respectively. Thus, the first FET 110 and the secondFET 120 are monolithically integrated in the one semiconductor die 101forming a half-bridge configuration.

The one semiconductor die 101 may include a semiconductor substrate,which may be, by way of example, a silicon substrate such as asingle-crystalline or multi-crystalline silicon substrate, a SiGesubstrate, a SiC substrate or a substrate of a semiconductor compoundsuch as A(III)-B(V), e.g., GaAs or GaN. The one semiconductor die 101may further include epitaxial semiconductor layers as well as doped andundoped portions, conductive structures, components, devices andinsulating structures which have previously been fabricated. The dopedportions may be formed by ion implantation and subsequent annealing orby diffusion, for example. In one embodiment, the only semiconductorelements of the one semiconductor die 101 are the first FET 110 and thesecond FET 120 in a half-bridge configuration. According to anotherembodiment, the one semiconductor die 101 includes, apart from the firstFET 110 and the second FET 120, further semiconductor elements anddevices such as resistors, capacitors, bipolar transistors, diodes, forexample. These further semiconductor elements and devices may constitutea monolithically integrated driver IC for the first and second FET. Byway of example, the contact areas 136, 137 of the first and second FETmay be contact plugs electrically connected to the driver IC,respectively, by conductive elements such as metal lines, for example.

The first FET 110 may be a lateral FET or a vertical FET such as atrench FET, for example. The first FET 110 may be of p-type or n-type.By way of example, the first FET 110 may be a Metal InsulatorSemiconductor FET (MISFET) such as a Metal Oxide Semiconductor FET(MOSFET), a Junction FET (JFET) or a High Electron Mobility Transistor(HEMT), e.g., a HEMT based on InGaAs/InP/AlInAs, AlGaN/GaN and Si/SiGehetero structures.

In the embodiment illustrated in FIG. 1, the one connection 111 ofsource/drain of the first FET 110 and the one connection 121 ofsource/drain of the second FET 120 are interconnected at the first side102 by a single contact area 130. According to another embodiment, theone connection 111 of source/drain of the first FET 110 and the oneconnection 121 of source/drain of the second FET 120 may be electricallycoupled to separate contact areas at the first side 102. These separatecontact areas may be interconnected, i.e. electrically coupled, bymounting the first side 102 of the one semiconductor die 101 on a leadframe.

The semiconductor device 100 may also include a second or furthersemiconductor dies such as driver ICs, for example. These furthersemiconductor dies may be electrically coupled to the one semiconductordie within a common package, e g. by bond wires.

FIG. 2 refers to a schematic cross-sectional view of a portion of asemiconductor device 200 including one semiconductor die 201, the onesemiconductor die 201 including a first n-type lateral DMOS 210 and asecond n-type lateral DMOS 220 in half-bridge configuration. The onesemiconductor die 201 includes an n⁺-type semiconductor substrate 240such as an n⁺-type silicon substrate and a p-type epitaxial layer 241formed on the n⁺-type semiconductor substrate 240. The p-type epitaxiallayer 241 constitutes a body region in both the first n-type lateralDMOS 210 and the second n-type lateral DMOS 220. At a first side 242 ofthe p-type epitaxial layer 241, semiconductor regions such as n-typedrain extension regions 243, p-type regions 244 used as channel regions,n⁺-type regions 245 used as source regions are formed within the p-typeepitaxial layer 241. In the first n-type lateral DMOS 210 conductiveplugs 246 electrically couple the n⁺-type semiconductor substrate 240 tothe n-type drain extension regions 243 formed at a first side 242 of thep-type epitaxial layer 241. The n⁺-type regions 245 of the second n-typelateral DMOS 220 are electrically coupled to the semiconductor substrate214 by the conductive plugs 246 such as C-plugs 246 (carbon) extendingthrough the p-type epitaxial layer 241. Thus, a source of the firstn-type lateral DMOS 210 and a drain of the second n-type lateral DMOS220 are electrically coupled via the n⁺-type semiconductor substrate 240at a first side 202 of the one semiconductor die 201. At the first side202, a metal layer or a metal layer stack may be formed on the n⁺-typesemiconductor substrate 240. A half-bridge configuration of the firstn-type lateral DMOS 210 as a high-side switch and the second n-typelateral DMOS 220 as a low-side switch may thus be achieved.

A drain of the first n-type lateral DMOS 210 is electrically coupled toa contact area 235 at a second side 203 of the one semiconductor die 201opposite to the first side 202 via second conductive plugs 247. Then⁺-type regions 245, i.e. source regions, of the second n-type lateralDMOS 220 are electrically coupled to a contact area 237 at the secondside 203 of the one semiconductor die 201 via the second conductiveplugs 247.

Gate regions 248 a of the first n-type lateral DMOS 210 surrounded by anisolation structure 249 are electrically coupled to a contact area atthe second side 203 of the one semiconductor die 201 (not illustrated inFIG. 2). Gate regions 248 b of the second n-type lateral DMOS 220 arealso electrically coupled to a contact area at the second side 203 ofthe one semiconductor die 201 (not illustrated in FIG. 2). The contactarea of the gate regions 248 a of the first lateral DMOS 210, thecontact area of the gate regions 248 b of the second lateral DMOS 220and the contact areas 235 and 237 are electrically separated from eachother, respectively.

A body region of the first lateral DMOS 210 being part of the p-typeepitaxial layer 241 may be connected to the n⁺-type semiconductorsubstrate 240 via a p⁺-type region 250 a adjoining the conductive plugs.The body region of the second lateral DMOS 220 being part of the p-typeepitaxial layer 241 may be connected to the contact region 237 via thesecond conductive plugs 247 and a p⁺-type region 250 b formed within thep-type epitaxial layer 241.

FIG. 3 illustrates a schematic cross-sectional view of a portion of asemiconductor device 300 including one semiconductor die 301, the onesemiconductor die 301 including an n-type lateral DMOS 310 and an n-typetrench FET 320 in half-bridge configuration.

Similar to the embodiment illustrated in FIG. 2, the one semiconductordie 301 includes an n⁺-type semiconductor substrate 340 and a p-typeepitaxial layer 341 formed thereon. Similar to the first n-type lateralDMOS 210 illustrated in FIG. 2, the n-type lateral DMOS 310 includesn-type drain extension regions 343, p-type regions 344 used as channelregions, n⁺-type regions 345 used as source regions, first and secondconductive plugs 346, 347, p⁺-type semiconductor regions 350 a adjoiningthe conductive plugs 346, gate regions 348 a and a contact region 335 ata second side 303 of the one semiconductor die 301.

The n-type trench FET 320 includes an n-type well region 351 as a drainformed within the p-type epitaxial layer 341 as well as a p-type bodyregion 352 formed within the p-type epitaxial layer 341. Trenches 353extend from a first side 342 of the p-type epitaxial layer 341 throughthe p-type body region 352 into the n-type well region 351. Within thetrenches 353, gate regions 348 b as well as part of an insulationstructure 349 are formed. N⁺-type source regions 345 are electricallycoupled to a contact area 347 at the second side 303 of the onesemiconductor die 301 via the second conductive plugs 347. The p-typebody region 352 is also electrically coupled to the contact area 337 viap⁺-type regions 350 b and the second conductive plugs 347. The gateregions 348 a, 348 b may be connected as described in the previousembodiment illustrated in FIG. 2.

A Schottky contact area 355 including a Schottky contact made of amaterial of the conductive plugs 347 and the n-type well region 351 isincluded in a cell array of the n-type trench FET 320. By electricallycoupling the source of the high-side n-type lateral DMOS 310 and thedrain of the low-side trench 320, a half-bridge configuration can beachieved. This half-bridge configuration including the Schottky contactarea 355 may be used in a DC/DC converter, for example.

FIG. 4 illustrates a schematic cross-sectional view of a portion of asemiconductor device 400 including one semiconductor die 401, the onesemiconductor die 401 including a p-type trench FET 410 and an n-typetrench FET 420 in half-bridge configuration. The one semiconductor die401 includes a semiconductor substrate 440 of p⁺-type in a region of thep-type trench FET 410 and of n⁺-type in a region of the n-type trenchFET 420. For example, a thickness of the semiconductor substrate 440 maybe several tens of micrometers, e.g., 40 μm and the semiconductorsubstrate 440 may be selectively doped, e.g., by diffusion prior to theformation of a p-type epitaxial layer 441 on the semiconductor substrate440. A drain of the p-type trench FET 410 and the drain of the n-typetrench FET 420 are electrically coupled via at least one conductivelayer such as a metal layer or metal layer stack formed at a first side402 of the one semiconductor die 401.

Similar to the n-type trench FET 320 described above with reference toFIG. 3, the n-type trench FET 420 includes an n-type well regionconstituting a drain of FET 420, a p-type body region 452, trenches 453having gate regions 448 b formed therein, an insulation structure 449which is also partly formed within the trenches 453, n⁺-type sourceregions 445 electrically coupled to a contact area 437 at a second side403 of the one semiconductor die 401 opposite to the first side 402 viaconductive plugs 447. The p-type body region 452 is electrically coupledto the contact area 437 via a p⁺-type region 450 b and the conductiveplugs 447.

The p-type trench FET 410 includes an n-type body region 460 formedwithin the p-type epitaxial layer 441, trenches 453 having gate regions448 a and part of the insulating structure 449 arranged therein, p⁺-typesource regions 450 a electrically coupled to a contact area 435 at thefirst side 403 of the one semiconductor die 401 via the conductive plugs447. The n-type body region 460 is electrically coupled to the contactregion 435 via the n⁺-type regions 445 and the conductive plugs 447.

The gate regions 448 a, 448 b may be electrically coupled to contactareas at the second side 403 as described above with reference to theembodiment illustrated in FIG. 2.

FIG. 5 refers to a schematic cross-sectional view of a portion of asemiconductor device 500 including one semiconductor die 501, the onesemiconductor die 501 including a first n-type trench FET 510 as ahigh-side switch and a second n-type trench FET 520 as a low-side switchin half-bridge configuration.

The one semiconductor die 501 includes an n⁺-type substrate 540 having afirst n-type epitaxial layer 541 a formed on the n⁺-type semiconductorsubstrate 540, a second p-type epitaxial layer 541 b formed on the firstn-type epitaxial layer 541 a and a third n-type epitaxial layer 541 cformed on the second p-type epitaxial layer 541 b. The second p-typeepitaxial layer 541 b constitutes a body region of both the first trenchFET 510 and the second trench FET 520.

Trenches 553 extend from a first side 542 of the third n-type epitaxiallayer 541 c into the first n-type epitaxial layer 541 a. Within thetrenches 553 of the first trench FET 510, gate electrode regions 548 aand part of an insulation structure 549 are formed, whereas in thetrenches 553 of the second trench FET 520, gate electrode regions 548 band another part of the insulation structure 549 are formed.

The first trench FET 510 furthermore includes first conductive plugs 546electrically coupling the second p-type epitaxial layer 541 b to then⁺-type substrate 540, n⁺-type source regions 565 formed within thefirst n-type epitaxial layer 541 a, n⁺-type drain regions 566 formedwithin the third n-type epitaxial layer 541 c as well as a contact area535 electrically coupled to the n⁺-type drain regions 566.

The second trench MOSFET 520 furthermore includes conductive spacers 567such as n⁺-type polysilicon spacers as source regions electricallycoupled to a contact area 537 at a second side 503 of the onesemiconductor side 501. Second conductive plugs 547 and p⁺-type regions550 b provide an electrical connection between the contact area 537 andthe second p-type epitaxial layer 541 b constituting a body region ofthe second trench FET 520.

FIG. 6 illustrates a schematic cross-sectional view of a portion of asemiconductor device 600 including one semiconductor die 601, the onesemiconductor die 601 including a half-bridge configuration of a firstn-type trench FET 610 as a high-side switch and a second n-type trenchFET 620 as a low-side switch.

Similar to the embodiment illustrated in FIG. 5, the one semiconductordie 601 includes an n⁺-type semiconductor substrate 640, a first n-typeepitaxial layer 641 a formed on the n⁺-type semiconductor substrate 640,a second p-type epitaxial layer 641 b formed on the first n-typeepitaxial layer 641 a, whereas distinct from the embodiment illustratedin FIG. 5, a third p-type epitaxial layer 641 c is formed on the secondp-type epitaxial layer 641 b.

In addition to n⁺-type regions 666 formed within the third p-typeepitaxial layer 641 c, the first trench FET 610 includes n-type zones670 laterally adjacent to trenches 653 and opposing each other betweenneighbouring trenches 653, the trenches 653 extending from a first side642 of the third p-type epitaxial layer 641 c into the first n-typeepitaxial layer 641 a. The n-type zones 670 and the n⁺-type regions 666constitute a drain of FET 610. Within the trenches 653, gate regions 648a and part of an insulating structure 649 is formed. The first trenchFET 610 furthermore includes n⁺-type source regions 665 formed withinthe first n-type epitaxial layer 641 a. First conductive plugs 646electrically couple the second p-type epitaxial layer 641 b to then⁺-type semiconductor substrate 640. Second conductive plugs 647 providean electrical connection of the n⁺-type drain regions 666 to a contactarea 635 at a second side 603 of the one semiconductor die 601.

The second trench FET 620 includes trenches 653 extending from the firstside 642 of the third p-type epitaxial layer 641 c into the first n-typeepitaxial layer 641 a. Within the trenches gate regions 648 b and partof the insulating structure 649 is formed. N⁺-type source regions 672are formed within the third p-type epitaxial layer 641 c, whereas n-typezones 671 laterally adjacent to sidewalls of the trenches 653 are formedbetween the n⁺-type source regions 672 and the second p-type epitaxiallayer 641 b opposing each other between neighbouring two of the trenches653. The n⁺-type source regions 672 are electrically coupled to acontact area 637 at a second side 603 of the one semiconductor die 601via the second conductive plugs 647. The second conductive plugs 647 andp⁺-type regions 650 b within the third p-type epitaxial layer 641 cprovide an electrical connection between the contact area 637 and thesecond p-type epitaxial layer 641 b constituting a body region of thesecond trench FET 620.

FIG. 7 illustrates a schematic cross-sectional view of a portion of asemiconductor device 700 including one semiconductor die 701, the onesemiconductor die 701 including a half-bridge configuration of a firstn-type trench FET 710 and a second n-type trench FET 720.

The one semiconductor die includes an n⁺-type substrate 740 having ap-type epitaxial layer 741 formed thereon. Trenches 753 including gateelectrodes 748 a, 748 b and part of an insulating structure 749 thereinextend from a first side 742 of the p-type epitaxial layer 741 into then⁺-type substrate 740. The p-type epitaxial layer 741 constitutes a bodyregion of both the first trench FET 710 and the second trench FET 720.The n⁺-type semiconductor substrate 740 constitutes a source of thefirst trench FET 710 and a drain of the second trench FET 720. N⁺-typeregions 766 formed in the p-type epitaxial layer 741 constitute drainregions of the first trench FET 710, the drain regions 766 beingelectrically coupled to a contact area 735 at a second side 703 of theone semiconductor die 701 opposite to a first side 702 via secondconductive plugs 747. First conductive plugs 746 electrically couple thep-type epitaxial layer 741 constituting a body region of the firsttrench FET 710 to the n⁺-type semiconductor substrate 740.

N⁺-type regions 772 formed in the p-type epitaxial layer 741 of thesecond trench FET 720 constitute source regions electrically coupled toa contact area 737 at the second side 703 of the one semiconductor die701 via the second conductive plugs 747. The p-type epitaxial layer 741constituting the body region of the second trench FET 720 iselectrically coupled to the contact area 737 via p⁺-type regions 750 band the conductive plugs 747. Semiconductor devices 700 may be used forlow-voltage applications, for example.

FIG. 8A illustrates a schematic plan view of a semiconductor device 800including a half-bridge configuration in one semiconductor die 801having a high-side FET and a low-side FET housed in a CanPAK package805. The one semiconductor die 801 has one of source/drain of thehigh-side FET and one of source/drain of the low-side FET electricallycoupled via a first side of the one semiconductor die 801 (notillustrated in FIG. 8A). The other one of source/drain of the high-sideFET is electrically coupled to a contact area 835 at a second side ofthe one semiconductor die 801 opposite to the first side, the other oneof source/drain of the low-side of FET is electrically coupled to acontact area 837 at the second side, a gate of the high-side FET iselectrically coupled to a contact area 836 at the second side and thegate of the low-side FET is electrically coupled to a contact area 838at the second side. The contact areas 835, 836, 837 and 838 areelectrically separated from each other, respectively.

FIG. 8B illustrates a schematic cross-sectional view along a cut lineAA′ of the semiconductor device 800 illustrated in FIG. 8A. The one ofsource/drain of the high-side FET is electrically coupled to the one ofsource/drain of the low-side FET via a contact area 830 at the firstside 802 of the one semiconductor die opposite to the second side 803.Although contact areas are formed on both sides of the one semiconductordie 801, all electrical connectors of the CanPAK package such asconnectors 839 a, 839 b, 839 c, 839 d are provided at a bottom side.

FIG. 8C illustrates a schematic cross-sectional view along a cut lineBB′ of the semiconductor device 800 illustrated in FIG. 8A. Similar tothe contact areas 835 and 837 illustrated in FIG. 8B, the contact areas836, 838 electrically coupled to the gates of the high-side FET and thelow-side FET are accessible via the connectors 839 d and 839 e providedat a bottom side of the CanPAK package 805.

In the simplified plan view of a printed circuit board (PCB) 809illustrated in FIG. 8D, the semiconductor device 800 is mounted on thePCB 809 having an input capacitance 825 soldered on the PCB 809. Theinput capacitance 825 is electrically coupled between the contact areas835 and 837 of the semiconductor device 800. The input capacitance 825may be located close to the connectors 839 b and 839 c of thesemiconductor device 800 to reduce parasitic inductance.

FIG. 9 illustrates a schematic cross-sectional view of the semiconductordevice 200 illustrated in FIG. 2 and an input capacitance 925electrically coupled between the contact areas 205 and 207, i.e. betweena drain of high-side FET 210 and a source of low-side FET 220, viasolder 926.

Placing the input capacitance 925 on the half-bridge configuration ofthe one semiconductor die 201, parasitic inductance may be reduced andthus voltage overshoots at a phase node of the half-bridgeconfiguration, i.e. at the drain of the low-side FET, may be reduced.Hence, the efficiency of synchronous rectification may be increased.

FIG. 10A illustrates a schematic plan view of a semiconductor device 100including the one semiconductor die 101 illustrated in FIG. 1 which ismounted on a lead frame 170 via the first side 102. An input capacitance125 is mounted on and electrically coupled to contact areas 135 and 137of the one semiconductor die 101, e.g., by solder. Bond wires 175 a, 175b electrically couple the contact areas 136, 138 of the high-side FET,the low-side FET of the one semiconductor die 101 to connectors 139 d,139 e. Conductive clips 178 a, 178 b electrically couple the contactareas 135, 137 to respective connectors 139 b and 139 c. The lead frame170 corresponds to a phase node of the half-bridge configuration and isaccessible via connector 139 a. The connectors 139 a, 139 b, 139 c, 139d, 139 e may correspond to an output pin such as V_(out), an input pinsuch as a supply pin V_(in), a ground pin, a gate pin for the high-sideswitch and a gate pin for the low-side switch, respectively.

In the schematic plan view illustrated in FIG. 10B, the semiconductordevice 100 is illustrated after moulding.

FIG. 11 illustrates a schematic plan view of a semiconductor device 100according to another embodiment. The embodiment illustrated in FIG. 11differs from the embodiment illustrated in FIG. 10A with regard toarrangement of the conductive clips 178 a, 178 b and the connectors 139a . . . 139 e. In the embodiment illustrated in FIG. 11, the lead frame170 is exposed to an outside of a package of the semiconductor device100. Therefore, the lead frame 170 equals the connector 139 a.

FIG. 12 illustrates a schematic plan view of a semiconductor device 100according to another embodiment. The embodiment illustrated in FIG. 12differs from the embodiment illustrated in FIG. 11 with regard toarrangement of the conductive clips 178 a, 178 b and input capacitance125. In the embodiment illustrated in FIG. 12, the input capacitance 125is electrically coupled to contact areas 135 and 137 of the onesemiconductor die 101 via the conductive clips 178 a, 178 b.

FIG. 13 illustrates a schematic plan view of a semiconductor device 100according to another embodiment. The embodiment illustrated in FIG. 13differs from the embodiment illustrated in FIG. 12 with regard toarrangement of the conductive clips 178 a, 178 b and the connectors 139a . . . 139 e. The embodiment illustrated in FIG. 13 furthermoreincludes connector 139 f electrically coupled to a first gate contactarea 138 a of the low-side FET and connector 139 e is electricallycoupled to a second gate contact area 138 b of the low-side FET. Via thecontact areas 138 a, 138 b different portions of the low-side switch maybe driven allowing for an improved efficiency of the low-side switchwith regard to load and frequency.

FIG. 14 illustrates a schematic plan view of a semiconductor device 100according to another embodiment. The embodiment illustrated in FIG. 14differs from the embodiment illustrated in FIG. 13 with regard toarrangement of the conductive clips 178 a, 178 b, connectors 139 a . . .139 f and input capacitance 125. In the embodiment illustrated in FIG.14, the input capacitance 125 is electrically coupled to and mounted oncontact areas 135 and 137 of the one semiconductor die 101.

FIG. 15 illustrates a simplified flow chart of a method of manufacturinga semiconductor device in accordance with a further embodiment. In S100a first and a second FET are formed within one semiconductor die,wherein one of source/drain of the first FET and one of source/drain ofthe second FET are electrically coupled to at least one contact area atthe first side of the one semiconductor die, respectively, and whereinthe other one of source/drain of the first FET, a gate of the first FET,the other one of source/drain of the second FET and the gate of thesecond FET are electrically coupled to contact areas at a second side ofthe one semiconductor die opposite to the first side, respectively, thecontact areas of the other one of source/drain of the first FET, of thegate of the first FET, of the other one of source/drain of the secondFET and of the gate of the second FET being electrically separated fromeach other, respectively.

FIGS. 16A-16K refer to a method of manufacturing a semiconductor deviceincluding a half-bridge configuration in a first and a second trench FETin one semiconductor die such as the one semiconductor die 501illustrated in FIG. 5.

According to FIG. 16A, a first n-type epitaxial layer 541 a is formed onan n⁺-type semiconductor substrate 540.

As illustrated in FIG. 16B, first conductive plugs 546 are formedthrough the first n-type epitaxial layer 541 a extending to the n⁺-typesemiconductor substrate 540 using a first mask 580. The first mask maybe a lithographically patterned mask.

Referring to FIG. 16C, a second p-type epitaxial layer 541 b is formedon the first n-type epitaxial layer 541 a. A third n-type epitaxiallayer 541 c is formed on the second p-type epitaxial layer 541 b.

As illustrated in FIG. 16D, trenches 553 are formed from a first side542 of the third n-type epitaxial layer 541 c extending into the firstn-type epitaxial layer 541 a using a second mask 581. The trenches 553may be formed by etching, for example.

As illustrated in FIG. 16E, spacers 582 are formed at sidewalls of thetrenches 553 and n-type dopants such as P or As are implanted into thefirst n-type epitaxial layer 541 a in a region of a to be formedhigh-side switch. The n-type dopants 583 are kept away from the regionof a to be formed low-side switch by a third mask 584.

As illustrated in FIG. 16F, after removing the masks 581, 584 and thespacers 582, gate electrode regions 548 a, 548 b and an insulatingstructure 549 are formed within the trenches 553. As an example, a gateoxide layer as part of the insulating structure 549 may be formedfollowed by deposition of polysilicon. After etching back thepolysilicon to form gate electrodes 548 a, 548 b, the trenches 553 maybe filled with oxide constituting a further part of the insulatingstructure 549. During formation of the insulating structure 549, then-type dopants 583 may diffuse forming n⁺-type source regions 565 in aregion of the to be formed high-side switch.

Referring to FIG. 16G, n-type dopants 585 are implanted into the thirdn-type epitaxial layer 541 c. An insulating layer is formed on the thirdn-type epitaxial layer 541 c constituting part of the insulatingstructure 549. Hence, the insulating structure 549 may include aplurality of dielectric materials such as silicon oxide, e.g., thermallygrown silicon oxide, boro-phosphor-silicate glass (BPSG),phosphor-silicate glass (PSG) and silicon nitride.

As illustrated in FIG. 16H, part of the insulating structure 549 ispatterned, e.g., by selective etching using lithography. The thirdn-type epitaxial layer 541 c is removed in a region of the to be formedlow-side switch by patterning. Patterning of the third n-type epitaxiallayer 541 c may be carried out by a mesa etch, for example.

As illustrated in FIG. 16I, dopants 585 are diffused forming n⁺-typedrain regions 566 in a region of the to be formed high-side switch.Diffusion of the dopants 585 may be achieved by thermal treatment.Furthermore, conductive spacers 567 such as n⁺-type polysilicon spacersare formed at sidewalls of the trenches 553 in a region of the to beformed low-side switch. P-type dopants are implanted into the secondp-type epitaxial layer 541 b and by appropriately selecting a dose ofthe p-type dopants 586, these dopants may also be implanted into thethird n-type epitaxial layer 541 c so that the formation of a furthermask on the third n-type epitaxial layer 541 c may be omitted. The doseof the p-type dopants 586 may be chosen such that these dopants do notcompensate the n-type dopants of the n⁺-type drain regions 566.

Referring to FIG. 16J, second conductive plugs 547, e.g., carbon (C)plugs, are formed between opposing two of the conductive spacers 567,e.g., by layer deposition and recess. A contact to the gate electrodes(not illustrated in FIG. 16G) may be provided at widened ends of thetrenches 553 by contact holes. These widened ends may be part of thetrenches 553 along a direction perpendicular to the drawing plane ofFIG. 16J.

As illustrated in FIG. 16K, contact areas 535, 537, e.g., metal layer(s)such as AlSiCu or TiW/Cu are formed by deposition and lithographicpatterning, the contact areas 535, 537 being electrically coupled ton⁺-type drain regions 566 of high-side FET 510, conductive spacers 567as source regions of low-side FET 520. Thus, the one semiconductor die501 includes monolithically integrated high-side FET 510 and low-sideFET 520 in half-bridge configuration.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations may besubstituted for the specific embodiments shown and described withoutdeparting from the scope of the present invention. This application isintended to cover any adaptations or variations of the specificembodiments discussed herein. Therefore, it is intended that thisinvention be limited only by the claims and the equivalents thereof.

1. A semiconductor device comprising: one semiconductor die having afirst and a second side opposite each other, and comprising a first anda second FET, wherein the first and the second FET are separated n-typechannel lateral FETs; wherein a first source/drain of the first FET anda first source/drain of the second FET are electrically coupled to atleast one contact area at the first side of the one semiconductor die;wherein a second source/drain of the first FET, a gate of the first FET,a second source/drain of the second FET and a gate of the second FET areelectrically coupled to contact areas at the second side of the onesemiconductor die; wherein the contact areas of the second source/drainof the first FET, of the gate of the first FET, of the secondsource/drain of the second FET and of the gate of the second FET areelectrically separated from each other; and wherein an electricalconnection from the at least one contact area at the first side to thefirst source/drain of the first and second FETs includes a firstconductive plug, and an electrical connection from the contact areas atthe second side to the second source/drain of the first and second FETsincludes a second conductive plug.
 2. The semiconductor device of claim1, further comprising a Schottky diode connected in parallel to thefirst and the second source/drain of the second FET.
 3. Thesemiconductor device of claim 1, wherein the one semiconductor diecomprises a stack of an n-type semiconductor substrate and a p-typeepitaxial layer on the n-type semiconductor substrate.
 4. Thesemiconductor device of claim 1, further comprising a package includinga single lead frame having the one semiconductor die mounted thereon viathe first side.
 5. The semiconductor device of claim 4, furthercomprising a capacitor arranged above the first side of the onesemiconductor die, the capacitor being electrically coupled between thecontact areas of source/drain of the first and second FETs at the secondside of the one semiconductor die.
 6. The semiconductor device of claim4, further comprising: conductive clips electrically coupled between thecontact areas of source/drain of the first and second FETs at the secondside of the one semiconductor die and pins of the package, respectively.7. The semiconductor device of claim 4, wherein the lead frame of thepackage is exposed on a side opposite to the side having the onesemiconductor die mounted thereon.
 8. A semiconductor device, comprisingone semiconductor die including a first n-type channel lateral FET andseparated therefrom a second n-type channel lateral FET, each lateralFET having a source, a drain, and a gate; wherein one of source/drain ofthe first FET and one of source/drain of the second FET are electricallycoupled to at least one contact area at a first side of the onesemiconductor die, respectively; wherein the other one of source/drainof the first FET, a gate of the first FET, the other one of source/drainof the second FET and the gate of the second FET are electricallycoupled to contact areas at a second side of the one semiconductor dieopposite to the first side, respectively; wherein the contact areas ofthe other one of source/drain of the first FET, of the gate of the firstFET, of the other one of source/drain of the second FET and of the gateof the second FET are electrically separated from each other,respectively; a package including a single lead frame having the onesemiconductor die mounted thereon via the first side; and wherein anelectrical connection from the at least one contact area at the firstside to one of the source/drain of the first and second FETs includes afirst conductive plug, and an electrical connection from the contactareas at the second side to the other one of the source/drain of thefirst and second FETs includes a second conductive plug.